Laundry detergent or cleaning product tablets with partial coating

Abstract

Partially coated laundry detergent and cleaning product tablets having advantageous properties such as high hardnesses without adverse effect on short disintegration times and high resistance to edge fracture are achieved with relatively small amounts of coating agents if the coating covers only mechanically sensitive parts of the tablets.

What is claimed is:  
     
       1. A compacted laundry detergent or cleaning product tablet having a surface and comprising: 
       i) at least one builder; and  
       ii) at least one surfactant, the tablet having a coating and the surface having one or more mechanically sensitive parts, wherein the coating covers only the one or more mechanically sensitive parts and no surface between those portions of two or more mechanically sensitive parts that are more than 10 mm apart.  
     
     
       2. The tablet of  claim 1 , wherein the coating covers not more than 80 percent of the total surface area of the tablet. 
     
     
       3. The tablet of  claim 1 , wherein the tablet has at least one corner which is a mechanically sensitive part and the coating covers said at least one corner. 
     
     
       4. The tablet of  claim 1 , wherein the tablet has at least one edge which is a mechanically sensitive part and the coating covers said at least one edge. 
     
     
       5. The tablet of  claim 1 , wherein the tablet has at least two edges which are both mechanically sensitive parts, and the coating covers from 1 to 60 percent of the distance between the two edges. 
     
     
       6. The tablet of  claim 1 , wherein the weight ratio of the uncoated weight of tablet to the weight of the coating is greater than 10:1. 
     
     
       7. The tablet of  claim 1 , wherein the coating has a thickness of from 0.1 to 3000 μm. 
     
     
       8. The tablet of  claim 1 , wherein the coating comprises at least one solid substance having a solubility in water of more than 200 g/l at 20° C. 
     
     
       9. The tablet of  claim 1 , wherein the coating comprises at least one carboxylic acid. 
     
     
       10. The tablet of  claim 1 , wherein the coating comprises at least one dicarboxylic acid. 
     
     
       11. The tablet of  claim 1 , wherein the coating comprises at least one film-forming substance. 
     
     
       12. The tablet of  claim 1 , wherein the coating comprises 0.1 to 10 percent by weight of at least one disintegration aid. 
     
     
       13. The tablet of  claim 1 , wherein the coating comprises 0.5 to 10 percent by weight of at least one cellulose-based disintegration aid. 
     
     
       14. The tablet of  claim 1 , wherein said at least one surfactant is present in an amount of more than 2.5 percent by weight and is selected from the group consisting of anionic surfactants and nonionic surfactants. 
     
     
       15. The tablet of  claim 1 , wherein the coating comprises at least one of the following polymers: 
       a) water-soluble nonionic polymers selected from the group consisting of:  
       a1) polyvinyl pyrrolidones,  
       a2) vinyl pyrrolidone/vinyl ester copolymers, and  
       a3) cellulose ethers;  
       b) water-soluble amphoteric polymers selected from the group consisting of:  
       b1) alkyl acrylamide/acrylic acid copolymers,  
       b2) alkyl acrylamide/methacrylic acid copolymers,  
       b3) alkyl acrylamide/methyl methacrylic acid copolymers,  
       b4) alkyl acrylamide/acrylic acid/alkylaminoalkyl (meth)acrylic acid copolymers,  
       b5) alkyl acrylamide/methacrylic acid/alkylaminoalkyl (meth)acrylic acid copolymers,  
       b6) alkyl acrylamide/methyl methacrylic acid/alkylaminoalkyl (meth)-acrylic acid copolymers,  
       b7) alkyl acrylamide/alkyl methacrylate/alkylaminoethyl methacrylate/alkyl methacrylate copolymers, and  
       b8) copolymers of:  
       b8i) unsaturated carboxylic acids,  
       b8ii) cationically derivatized unsaturated carboxylic acids, and  
       b8iii) optionally other ionic or nonionic monomers;  
       c) water-soluble zwitterionic polymers selected from the group consisting of:  
       c1) acrylamidoalkyltrialkylammonium chloride/acrylic acid copolymers and alkali metal and ammonium salts thereof,  
       c2) acrylamidoalkyl trialkylammonium chloride/methacrylic acid copolymers and alkali metal and ammonium salts thereof, and  
       c3) methacroyl ethyl betaine/methacrylate copolymers;  
       d) water-soluble anionic polymers selected from the group consisting of:  
       d1) vinyl acetate/crotonic acid copolymers,  
       d2) vinyl pyrrolidone/vinyl acrylate copolymers,  
       d3) acrylic acid/ethyl acrylate/N-tert.butyl acrylamide terpolymers,  
       d4) graft polymers of vinyl esters, esters of acrylic acid or methacrylic acid individually or in admixture copolymerized with crotonic acid, acrylic acid or methacrylic acid with polyalkylene oxides and/or polyalkylene glycols,  
       d5) grafted and crosslinked copolymers from the copolymerization of:  
       d5i) at least one monomer of the nonionic type,  
       d5ii) at least one monomer of the ionic type,  
       d5iii) polyethylene glycol, and  
       d5iv) a crosslinking agent,  
       d6) copolymers obtained by copolymerization of at least one monomer of each of the following three groups:  
       d6i) esters of unsaturated alcohols and short-chain saturated carboxylic acids and/or esters of short-chain saturated alcohols and unsaturated carboxylic acids,  
       d6ii) unsaturated carboxylic acids, and  
       d6iii) esters of long-chain carboxylic acids and unsaturated alcohols and/or esters of the carboxylic acids of group d6ii) with saturated or unsaturated, linear or branched C 8 -C 18  alcohols,  
       d7) terpolymers of crotonic acid, vinyl acetate and an allyl or methallyl ester,  
       d8) tetrapolymers and pentapolymers of:  
       d8i) crotonic acid or allyloxyacetic acid,  
       d8ii) vinyl acetate or vinyl propionate,  
       d8iii) branched allyl or methallyl esters, and  
       d8iv) vinyl ethers, vinyl esters or straight-chain allyl or methallyl esters,  
       d9) crotonic acid copolymers with one or more monomers from the group consisting of ethylene, vinyl benzene, vinyl methyl ether, acrylamide and water-soluble salts thereof, and  
       d10) terpolymers of vinyl acetate, crotonic acid and vinyl esters of a saturated aliphatic monocarboxylic acid branched in the α-position; or  
       e) water-soluble cationic polymers selected from the group consisting of:  
       e1) quaternized cellulose derivatives,  
       e2) polysiloxanes containing quaternary groups,  
       e3) cationic guar derivatives,  
       e4) polymeric dimethyl diallylammonium salts and copolymers there of with esters and amides of acrylic acid and methacrylic acid,  
       e5) copolymers of vinyl pyrrolidone with quaternized derivatives of dialkylaminoacrylate and methacrylate,  
       e6) vinyl pyrrolidone/methoimidazolinium chloride copolymers,  
       e7) quaternized polyvinyl alcohol, and  
       e8) polymers known by the INCI names of polyquaternium 2, polyquaternium 17, polyquaternium 18 and polyquaternium 27.  
     
     
       16. A method of producing a coated laundry detergent or cleaning product tablet according to  claim 1 , the method comprising the steps of: 
       a) compressing a p articulate detergent or cleaning product to form a tablet, wherein the tablet has one or more mechanically sensitive parts; and  
       b) covering said one or more mechanically sensitive parts with a coating comprising at least one coating material, wherein the coating does not cover the entire surface area of the tablet.  
     
     
       17. The method of  claim 16 , wherein covering step b) takes place by spraying said one or more mechanically sensitive parts with a melt, solution, emulsion or dispersion comprising the one or more coating materials. 
     
     
       18. The method of  claim 16 , wherein covering step b) takes place by immersing said one or more mechanically sensitive parts in a melt, solution, emulsion or dispersion comprising the one or more coating materials. 
     
     
       19. The method of  claim 16 , wherein the covering step b) takes places by applying a melt to said one or more mechanically sensitive parts, and the melt is at a temperature of from 40 to 100° C. 
     
     
       20. The method of  claim 16 , wherein the coating is applied with at least one inert propellant selected from the group consisting of air, nitrogen, dinitrogen oxide, propane, butane, and dimethyl ether, further wherein the coating comprises at least one solvent selected from the group consisting of water, methanol, ethanol, 1-propanol, 2-propanol, diethyl ether, and n-heptane.